Properties of SmCo Film for Magnetic Rotary Encoder

RF magnetron sputtering was used to prepare SmCo films on drums for use in magnetic rotary encoders and the recording and playback characteristics were investigated. It was found that for a head-medium spacing of 15 μm, recording and playback with an S/N ratio of at least 30 dB was possible at bit lengths as short as 50 μm, corresponding to a maximum resolution of approximately 3150 PPR when adopted in ordinary 50 mm diameter encoders.